Confirmation of the presence or absence of HCMV gene expression in myeloid progenitors by RT-PCR. RNA extracted from myeloid progenitors on days 1, 2, 3, 5, and 11 after infection was examined by RT-PCR for the expression of UL68, UL50, and UL120 transcripts for 40 cycles of amplication. Controls included the omission of reverse transcriptase (RT), samples from either mock-infected myeloid progenitor cells or HFs (Mock), productively infected HFs (Pos), or samples without any added template (Neg). Marker was GeneRuler DNA ladder mix (Fermentas).